Dooku: "There's a sith called Darth Sidious doing all this shit fam"

Wasn't Darth Bane's issue that there were loads of Sith and the whole Sith order was in stagnation so he decided it'd be better to get rid of most of them, let the Jedi think they'd all disappeared and instead have a chain of masters and apprentices passing down their accumulated Sith knowledge?
I think it was a rule, anything more than 2 leads to self-destructive infighting.